Pawl control



Ell. D. WLTON inf/14M W ATTORNEY Jan. 7, 1958 N. D. WALTON PAwL CONTROL Filed Nov. 19,- 1954 3 Sheets-Sheet 1 Jan. 7, 1958 N. D. WALTQN 2,818,959

PAwL CONTROL Filed Nov. 19, 1954 3 Sheets-Sheet 2 INVENTOR. NEIL D, WALTON Y f u) y ma w m41/ ATTORNEY Jan. 7, 1958 N. D. wALToN 2,818,959

PAWL CONTROL Filed Nov. 19, 1954 3 Sheets-Sheet 3 INVENTOR. L D. WALTON 3 in response to the rocking of the intermediate pawl release bell crank 16 acting through stud 20.

The intermediate grouping lever 31 has a finger 33 engageable with a grouping lever 35 pivoted on a `stud 4t) and having an extension 37, including a bent over iinger 39 passing through corresponding openings in all of the pawls 26.

Counterclockwise rotation of the intermediate grouping lever 31 about supporting stud 18, yas a result of rocking of stud 20, rotates the grouping lever 35 clockwise causing the finger 39 to push the -corresponding edges 4l of all the pawls 26 into grouped position (see Figs. 5 and 6). lntermediate grouping lever 31 further has a catch portion 32 engageable with a grouping latch 34, after intermediate grouping lever 31 has been rotated counterclockwise to the position shown in Fig. 3, whereupon a spring 36 pulls on the latch 34 lthereby pivoting it about its support 35a into locking engagement with the catch portion 32. T his latching operation holds the pawls grouped and retains lthem in grouped position, as shown in Fig. 6, so that the proper pawl will engage the assigned rack tooth for a proportional escapement operation. As will be explained in greater detail, the pawls will be latched in grouped position, while the carriage moves through the lett hand margin into overbank and settles down at the left hand margin. As the carriage moves from overbank into the left hand margin position, one of the pawls will strike the assigned rack tooth, which in turn, willL push on the pawl to release the grouping latch, whereupon the pawls will be in their proper sequence position for a proportional escapement operation, and the carriage will be at the correct left hand margin position. The pawls are unlatched as follows: An unlatching lever 38 is pivotally mounted on stud 40 carried by the typewriter frame in position to be rocked by an ear 42 of the pawls. More particularly, the pawl engaging end 44 of unlatching lever 38 is bent over to provide a lip 46 long enough to engage only the ear 42 on either the number 4 or 8 pawl, the shortest pawl, respectively, of each of the two groups described in the aforementioned Dodge Patent 2,547,499. These pawls are juxtapositioned as shown in Fig. and 6, and either pawl in engaging a rack tooth will unlatch the grouping latch 34 and position the pawls in proper sequence in the rack (Fig. 5). The ear 42 of the 4 or 8 pawl in engaging the lip 46 will rock the release lever 38 clockwise (Fig. 3) about its pivot 4th, whereupon the release lever will pull on a pin 48 carried by a latch release arm 5t) to rotate the latter counterclockwise about its supporting pivot 35a. Latch release arm Sti is adjustably connected by a set screw arrangement 51 to the grouping latch 34. Accordingly, when either the 4 or 8 pawl pushes on the lip 46 to rock the unlatched lever 38 clockwise, the trip latch 34 will be rocked counterclockwise, thereby disengaging the latch from the shoulder 32 thus permitting the pawls to become ungrouped, and assume their Fig. 5 position.

It has been previously mentioned that a pull on link 8 (Figs. l and 4) will hold the pawls out of the escapement rack and latch them out and in grouped position, The pawls should be dropped back in the rack in grouped Varrangement within approximately a quater of an inch of the left hand margin. This action is accomplished in the following manner: Referring specifically to Fig. l and Fig. 4, it will be noticed that the arm 8 carries a latch ear 52 and that it is mounted by means of :an elongated aperture 56 for sliding movement on a stud 54 (carri-ed by the typewriter frame). The arm 12 is also slidably mounted on the stud 54 within the limits of its elongated aperture 56a and the arm has `a complementary hook portion 58 engageable with ear 52 of arm S to form the latch 1t). The pull on link 14 in response to clockwise pivoting of bell crank 2 takes place only when the ears 52 and 58 are in engagement. lf this latch connection is broken, the arm 12 will move to the right 'to the position shown in Fig. l so that 'the left hand end of aperture 56a is in engagement with the stud 54. This position of arm 12 will release the pull on link 14 thereby permitting the pawls to drop back into engagement with the escapement rack. In accordance with the teachings of this invention, the arm 12 is rocked clockwise about the pivot stud 54 when the carriage reaches a position within a quarter of an inch of the left hand margin, thereby releasing the ear 52 from S8 permitting the link 14 to be released so that the pawls will be dropped back into the escapement rack.

ln this respect, the carriage is provided with a movable margin stop 6i), which is adjustable on margin rack 6l to determine the margin position. When the carriage is moved towards the left hand margin position, which will be from right to left in Fig. l, the carriage margin stop 6@ will come into contact with the margin lever which is slidably mounted on the typewriter frame by means of the studs 66 and elongated apertures 68. The margin lever includes an ear 70 engageable with a finger 72, an integral part of a margin control lever 74, which is pivotally supported at 76 on the typewriter frame. The margin control lever 74 in turn has an operating ear 7S engageable with an air cushion bell crank 3) which is pivoted on stud 54 and has an actuating arm 82 for pushing on a rod 84, that carries a piston 86 of an air cylinder 88. With this structure, when the carriage moves into the left hand margin position, the nger 72 is moved counterclockwise about its supporting stud '76 by margin lever 64 thereby actuating the air cylinder 88 to absorb the shock of the carriage. Simultaneously, the air cylinder arm St) which has an integral portieri, an unlatching lever 949, is rocked clockwise about the stud 54 thereby acting upon an ear 92 to disengage the ear S2 from the hook 58 unlatching the arm 12 so the tension is taken off the link 14 whereupon the pawls are allowed to drop back into the escapement rack. It will be noted that this latter operation takes place within the time and distance that it takes the carriage to travel the difference between the elongated aperture 68 and the stud 66.

Starting from the depression ot the carriage return button, the escapement pawls will be latched out of the escapement rack and grouped until the carriage returns within a quarter of an inch of the left hand margin position whereupon the operation of the margin stop in conjunction with the linger 72 will unlatch the arm 12 to release the tension on link 14 thereby permitting the pawls to drop back into the escapement rack but holding the pawls grouped and latched in the grouped position. Plhe pawls will stay in the grouped position until the carriage has passed the left hand margin into the overbank position and back to the left hand margin again, at which time they will be ungrouped, and assume the position shown in Fig. 5

Tabulation As is more particularly described in United States Patent 1,935,436, a tabulation operation is instituted by a power cam operating in conjunction with the power roll and pushing on a bell crank to exert a force into the plane of the paper (as viewed in Fig. l) against a tab lever 10i). The latter is pivotally mounted for clockwise and counterclockwise movement as viewed in Fig. l about the stud 102, so that the nose ltl' of a tab check lever 164 (mounted on tab lever 180 by means of studs 66), Figs. 1 and 4, is movable counterclockwise and latched in a tab checking position as described in aforesaid Patent 1,935,436, when the tabulating mechanism is operated. This counterclockwise motion of tabulating lever (acting through integral extension 107), Fig. 4, exerts a force on a iinger 106 and consequently, on an ear 108 which, in turn, is in contact with an extension 110 (see Figs. 2 and 3 also) of the intermediate pawl release bell crank 16 which has been previously mentioned as being pivoted on the stud 18. This push on the finger 110 will rock the intermediate pawl release bell crank about the stud 18 to exert a thrust on stud 20 thereby grouping the pawls 26 through the mechanism previously described and rocking the intermediate grouping lever 31 so that the grouping latch will engage the shoulder 32 thereby holding the pawls in grouped arrangement until they are unlatched by the 4 or 8 pawl striking a tooth in the escapement rack as has heretofore been described.

When the nose 105 of the tab check lever 104 strikes a tab stop, the tab lever will be unlatched as described in United States Patent 1,935,346, whereupon the tab lever is restored to its Fig. 4 position. With the restoring of the tab lever, the ear 10S is removed from the path of the finger 110 so that the pawls will drop back into the rack; but it will be noted that the pawls will still be grouped and latched by the inter-action of the grouping latch 34 and the shoulder 32. This grouping of the pawls will exist until the 4 or the 8 pawl strikes the proper tooth on the escapement rack to unlatch the grouping latch as has heretofore been described. It is important to note that with the mechanism shown, the pawls are grouped and latched in the grouped position both for a carriage return operation and during a tabulation run, and consequently, it is apparent that for any carriage movement with the pawls grouped and latched in the grouped position, the pawls will always be unlatched and arranged in their proper sequence for a proportional spacing operation by the 4 or 8 pawl butting against a tooth of the escapement rack.

The tabulation will override the carriage return operation Referring to Fig. 2 of the drawings, an vautomatic grouping lever 112 is shown mounted for pivotal movement about a stud 114 carried by the typewriter frame. The automatic grouping lever 112 has an outer arm 116 which is provided with an aperture 118 for housing a pull link 120 which is also shown in Fig. l of the drawings. Pull link 120 is connected to a bell crank 122, which is mounted on the stud 6 to be movable independently of the bell crank 2. It will be noted that counterclockwise rotation of the automatic grouping lever 112 about its supporting stud 114 will exert a pull on the link 12@ opposite in direction from the pull exerted on the arm S when the bell crank 2 is operated by the carriage return mechanism (see arrows). As shown in copending application, Serial No. 469,915, filed November 19, 1954, the pull to the right in Fig. l of the drawings on link 120 will disable the carriage return mechanism to the extent that the clutch will be prevented from latching up. In addition, if the carriage return clutch has been operated and latched, then the pull on link 121) will unlatch the carriage return clutch.

With reference to Figs. 2 and 4 of the drawings, the tab lever 100 includes an integral button 124 which is rotated counterclockwise during a tab operation as heretofore described. A bell crank 126 is positioned on a stud 128 for engagement with the button 124 so that during a tab operation, the bell crank 126 will be rocked counterclockwise about the stud 12S whereupon an extension 130 (Fig. 4) will engage an ear 132 carried by the automatic grouping lever 112. With this operation, it is obvious that every time the tabulating mechanism is set, the inter-engagement of the extension 130 and the ear 132 will rock the automatic grouping lever 112 counterclockwise about its supporting stud 114 thereby exerting a pull on link 120 in the direction of the arrow shown in Fig. 1 so as to disable the carriage return clutch latch to prevent the carriage return clutch from latching up during a tabulating run.

A grouping operation for a manual carriage return Referring to Fig. 2, it will be noticed that the automatic grouping lever 112 has an extension 133 which is positioned for engagement with a finger 134 carried by the margin control lever 74 (see Fig. l).

Referring now to Fig. l of the drawings, it Will be noted that as the carriage is moved to the left hand margin position, the margin stop 6U engages the margin lever 64 which is axially slidable within the limits of the difference between the apertures 68 and the studs 66. lt has been mentioned how the margin lever 64 carries an ear 70 which operates on the finger 72 to rotate the margin control lever 74. The finger 134 is secured by screws 136 to the margin control lever 74. Accordingly, as the carriage moves into a left hand margin position, the linger rotates the margin control lever 74, whereupon the finger 134 will push on the extension 133 of the automatic grouping lever thus causing its outer end 116 to push upon the intermediate grouping lever 31 rocking that counterclockwise about its supporting stud 18 as has heretofore been described.

The counterclockwise rotation of the intermediate grouping lever 31 causes the finger 33 to rotate the grouping lever 35 clockwise to group the pawls and also causes the grouping latch 34 to engage the shoulder 32 on the intermediate grouping lever 31. Accordingly, by the mechanism described, as the carriage is pulled manually into the left hand margin position, the pawls will be grouped and latched in the grouped position until the carriage is released and allowed to settle at the left hand margin. In doing this, the 4 or 8 pawl will engage the assigned rack tooth and unlatch the grouping latch 34 permitting the pawls to assume their ungrouped position, shown in Fig. 5.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. lt is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. In a typewriter having a power operated carriage return mechanism and an escapement pawl spring biased into releasable engagement with a typewriter escapement rack for effecting an escapement operation, a pawl control device for lifting said escapement pawl out of the escapement rack during a carriage return operation and for holding said escapement pawl out until the carriage reaches a predetermined distance from its left hand mar gin position, said pawl control device comprising a bell crank, means pivotally mounting the same on the typewriter frame for rocking movement from an inoperative to an operative position in response to a carriage return operation, an escapement pawl release lever mounted on said typewriter frame for movement into and out of a position to lift said pawl out of said escapement rack in opposition to said spring biasing means, and actuating means for moving said pawl release lever into its lifting position comprising a two piece link interconnecting said bell crank and said pawl release lever, a releasable latch in said link normally interconnecting said two link pieces, and adjustable means operable in response to the movement of the carriage toward its left hand margin position for releasing said latch to disengage said pawl release lever from said bell crank thereby permitting said pawl to drop back into said escapement rack irrespective of the position of said bell crank.

2. In a typewriter having a power operating carriage return mechanism and an escapement pawl spring biased into releasable engagement with a typewriter escapement rack for effecting an escapement operation, a pawl control device for lifting said escapement pawl out of the escapement rack during a carriage return operation and for holding said escapement pawl out until the carriage reaches a predetermined distance from its left hand margin position, said pawl control device comprising a bell crank, means pivotally mounting the same on the typewriter frame for rocking movement from an inoperative to an operative position in response to a carriage return operation, an escapement pawl release lever mounted on said typewriter frame for movement into and out of a position to lift said pawl out of said escapement rack in opposition to said spring biasing means, and actuating means for moving said pawl release lever into its lifting position comprising a two piece link interconnecting said bell crank and said pawl release lever, a releasable latch in said link normally interconnecting said two link pieces, and adjustable means operable in response to the movement of the carriage toward its left hand margin position for releasing said latch to disengage said pawl release lever from said bell crank thereby permitting said pawl to drop back into said escapement rack irrespective of the position of said bell crank, said latch releasing means comprising a margin lever pivotally mounted on said typewriter frame for movement into and out of an operative position as said carriage approaches its left hand margin position, and means interconnecting said margin lever and said link latch to release the latter as said carriage approaches its left hand margin position.

3. ln a typewriter having a power operated carriage return mechanism and an escapement pawl spring biased into engagement with an escapement rack for effecting an escapement operation, a pawl control device for releasing said escapement pawl from the carriage escapement rack during a carriage return operation and for holding said pawl released until the carriage reaches a predetermined number of letter spaces before the left hand margin position and for holding the escapement pawl in the rack so long as the carriage is within a predetermined number ot letter spaces from the left hand margin position, said pawl control device comprising a pawl release lever pivotally mounted on the typewriter frame for movement into and out oi' a position for releasing said escapement pawl from the carriage rack in opposition to the pawl biasing means, a bell crank pivotally mounted on said typewriter frame and rockable in response to a carriage return operation from a rest position to a latched position, a two piece link device including a latch normally holding said two pieces in engagement interconnecting said bell crank and said pawl release lever whereby during a carriage return operation when the bell crank is rocked to its latched position said link device pulls on said pawl release lever to pivot the same and release the escapement pawl from the escapement rack, a margin lever pivotally mounted on said typewriter frame for rocking movement in response to the typewriter carriage moving through a predetermined number of letter spaces before its left hand margin position, and a latch trip arm interconnecting said margin lever with said link latch to release the latter to disconnect said pawl release lever from said bell crank thereby permitting said escapement pawl to drop back into the escapement rack irrespective of the of the latched condition of said bell crank, said trip arm preventing said link latch from interconnecting the two pieces of said link so long as the carriage is within said predetermined number ot' letter spaces from the left hand margin position.

4. ln a typewriter having a power operated carriage return mechanism and a plurality of pawls engageable with the escapement rack for a proportional escapement operation, a device for grouping the plurality of pawls during a carriage return operation and latching them in grouped 6 position until the carriage stops at an assigned position,

said device comprising a pawl grouping lever pivoted on said typewriter frame, means operable in response to a carriage return operation for rocking said grouping lever from a rest position to a grouping position to group said pawls, a latch for locking said grouping lever in pawl grouping position after said plurality of pawls have been grouped, a grouping latch release, and means operable in response to a predetermined pawl striking an assigned rack tooth to operate said grouping latch release to ungroup said pawls.

5. In a typewriter having a power operated tabulating mechanism and a plurality of pawls engageable with an escapement rack for effecting a proportional escapement operation, a device for grouping the plurality of pawls during a tabulation run of the carriage and latching them in grouped position until the carriage stops at an assigned position, said device comprising a pawl grouping lever pivotally mounted on the typewriter frame to group the pawls as said grouping lever is pivoted into a grouping position, means operable in response to a tabulating operation for rocking said grouping lever from a rest position to a grouping position to group said pawls, a latch for locking said grouping lever in pawl grouping position after said pawls have been grouped, a grouping latch release, and means operable in response to a predetermine-d pawl striking an assigned rack tooth to operate said latch release to ungroup said pawls.

6. In a typewriter having a power operated carriage return mechanism and a plurality of pawls engageable with an escapement rack to elect a proportional escapement Operation, a device for releasing the pawls from the escapement rack during a carriage return operation and for dropping the pawls back into the rack in a grouped relationship before the carriage reaches a left hand margin position, said device comprising a pawl release lever pivotally mounted on the typewriter frame for rocking movement from a rest position to 'a pawl releasing position, a bell crank pivotally mounted on said typewriter frame for movement into a latched position in response to a carriage return operation, a two piece link device including a link latch for holding the link parts normally in assembled relationship to interconnect said bell crank and said pawl release lever thereby rocking the latter to a pawl releasing position during a carriage return operation, a grouping lever pivotally mounted on said typewriter frame or rocking movement into a pawl grouping position in response to the rocking of said pawl release lever, a latch for locking said pawl grouping lever in pawl grouping position after said pawls have been grouped, a link latch release, a margin lever pivotally mounted on said typewriter frame to be rocked in response to the carriage traversing a predetermined number of letter spaces before the lleft hand margin position, a trip lever interconnecting said margin lever and said link latch whereby said link latch is released to permit said pawls to drop back into their escapement rack in response to the rocking of said margin lever, a grouping latch release, and means operable in response to a predetermined pawl striking an assigned rack tooth to operate said grouping latch release to ungroup said pawls.

References Cited in the le of this patent UNITED STATES PATENTS 

